Search PubMed⌕ Search

Biomedical subjects

C Abrahams

Publications and source records attributed to C Abrahams.

At least 37 records · Page 2Linked to original sources
PubMed1988

Collagen network remodelling and diastolic stiffness of the rat left ventricle with pressure overload hypertrophy.

This study had two objectives: (a) to determine the accumulation of collagen and its structural remodelling in the hypertrophied rat left ventricle after 4 and 8 weeks of abdominal aorta banding; and (b) to correlate these findings with the diastolic stress-strain relation of the intact myocardium. In comparison to age and sex matched controls, the collagen volume fraction of the hypertrophied myocardium after 4 and 8 weeks of aortic banding increased significantly from 3.5(SD1.0)% to 7.8(4.2)% and 6.2(2.0)% respectively. This accumulation of collagen, or fibrosis, occurred in the absence of myocyte necrosis. Scanning electron microscopy showed increased density and thickness of the collagen weave and tendons. At 4 weeks, light microscopy showed interstitial oedema and disrupted collagen fibrils. Left ventricular diastolic stress-strain relations of both pressure overload groups were significantly steeper than that of the control group. Thus the response of the interstitium to the hypertrophic process that accompanies abdominal aorta banding is a complex process that includes a structural remodelling of the fibrillar collagen matrix and the early appearance of interstitial oedema, each of which may contribute to a rise in the passive stiffness of the intact myocardium.

Animals↗
PubMed1988

Crystalline inclusions associated with lung adenomas in C57BLxC3H F1 mice.

In a study on lung adenomas induced by the administration of a single intragastric dose of sodium thiocyanate, diethylnitrosamine, or its precursors to 15-day-old C57BLxC3H F1 mice the occurrence of crystalline inclusions in pulmonary parenchyma was noted. A correlation between crystalline deposits and number and type of adenomas seen between 46 and 110 weeks was observed. In 45/61 adenomas, eosinophilic cells containing inclusions were seen scattered in the pulmonary tissue, adjacent to tumor areas, in desquamated cells in the bronchioles, in the lumens of the submucosal bronchial glands, and within the alveoli. By contrast 7/85 mice without adenomas showed inclusions (4/7 mice had pneumonitis). The inclusions stained with bromophenol blue, were PAS positive diastase resistant and showed varying amounts of alpha-1-antitrypsin, IgG, and IgA by immunoperoxidase technique. Ultrastructure revealed membrane bound rods with a lattice pattern.

Adenoma↗
PubMed1987

Recanalization of obstructed arteries with a flexible, rotating tip catheter.

A flexible, rotating tip catheter (Kensey catheter) was used to recanalize 24 segments of diseased superficial femoral arteries (from cadavers) that were sewn as xenografts into the femoral, carotid, or aorticorenal arteries of 14 dogs. One perforation occurred; there were emboli in some brains and kidneys, the consequences of which remain unknown. No signs of gross neurologic deficits or limb ischemia were seen at 0-11 days.

Angiography↗
PubMed1987

Hyperoxia-induced converting enzyme insufficiency in conscious rat: cardiovascular effects.

The effects of exposing rats to hyperoxia (100 percent O2) at normal atmospheric pressure for periods of 24-48 hours on components of the renin-angiotensin system and on blood pressure control were examined. Intrapulmonary conversion of angiotensin I (AI) to angiotensin (AII) was assessed using an isolated lung preparation perfused at constant flow. Exposure of rats to hyperoxia for 44-48 hours reduced single pass conversion of AI to AII in the pulmonary circulation from control levels of 82 +/- 4 to 29 +/- 5 percent (p less than 0.001). AII levels in trunk blood of 44-48 hour O2 exposed animals were 5.2 +/- 1.9 pg/ml, compared to 37.9 +/- 10.0 pg/ml in controls (p less than 0.001). Mean arterial pressure decreased significantly from 117 +/- 4.3 to 103 +/- 6.7 mmHg (p less than 0.05) in the O2 exposed group despite a threefold increase in plasma renin activity. The pressor response to exogenous AI was significantly diminished by O2 exposure, while the pressor response to exogenous AII remained unchanged from control. Pulmonary angiotensin-converting enzyme activity fell to approximately 50 percent of control in O2 exposed animals, but circulating converting enzyme activity was not change in this group. None of these alterations was apparent following 24 hours of hyperoxic exposure. These data suggest that O2 induced impairment in activity of angiotensin-converting enzyme at the endothelial membrane level has functionally significant effects on cardiovascular homeostasis, probably via reduced generation of endogenous AII.

Angiotensin I↗
PubMed1987

Collagen in the hypertrophied, pressure-overloaded myocardium.

The extracellular structural protein, collagen, is responsible for the functional integrity of the myocardium permitting reversible interdigitation and transmission of force between contracting myocytes. In the pressure-overloaded, hypertrophied myocardium, clinical and experimental evidence indicates that the proportion of collagen relative to muscle is increased. Factors that appear to influence collagen growth during the hypertrophic process include age, species, the rapidity with which the overload occurs, the nature of the lesion leading to the pressure-overload, and the severity and duration of the overload. Morphologically, the heart's collagen matrix consists of a complex weave with tendinous insertions that surrounds myocytes grouping them into myofibers, strands of collagen that connect adjoining myofibers, and collagenous struts that join myocytes to other myocytes and capillaries. In a primate preparation of perinephritis with systemic hypertension, it was observed that the tendinous elements of the weave and the strands of collagen lying between myofibers were increased in number and physical dimension. The functional consequences of a remodeling of the collagen matrix that accompanied myocardial hypertrophy remain to be elucidated. A better understanding of the dynamic behavior of the collagen matrix may offer new insights into the pathogenesis of ventricular dysfunction that accompanies the chronic pressure-overloaded state.

Animals↗
PubMed1987

Myocardial hypertrophy in Macaca fascicularis. Structural remodeling of the collagen matrix.

The collagen skeleton in the myocardium of 37 non-human primates (Macaca fascicularis) was studied by scanning electron microscopy. Twenty-one hypertensive animals had "pressure-overload" myocardial hypertrophy of 4 to 80 weeks duration induced by unilateral perinephric cellophane insertion and 16 were normotensive controls. The purpose of the study was to examine possible remodeling of the collagen matrix of the hypertrophied pressure overloaded M. fascicularis myocardium. An extensive collagen matrix was demonstrated in nonoperated macaques, consisting of a weave which sequestered groups of myocytes and which was joined to the epimysium by long collagen tendons, and of numerous intermyocyte and myocyte to capillary struts. In addition, strands of collagen were seen crossing interfascicular planes. This collagen skeleton was studied at three periods of perinephritis-induced hypertension with hypertrophy: at 4 weeks (evolutionary); at 32 weeks with mild to moderate hypertension (early compensatory); and at 80 weeks with moderately severe hypertension (late compensatory). These sequential studies revealed that the matrix was remodeled. At 4 weeks there was slight thickening and increase in density of the weave. At 32 weeks, in addition to changes in the weave, the collagen strands became thick and pillar-like and the tendons increased in numbers and thickness, and at 80 weeks some myocytes became encased in collagen. The geometrical arrangement of the normal collagen matrix of the myocardium is similar to series and parallel elastic elements with respect to myocytes, and, accordingly, it may be responsible for the mechanical properties of the myocardium during diastole and systole. The structural alterations in the collagen skeleton which we observed in hypertrophy may play a significant role in deleteriously affecting ventricular function of the pressure-overloaded myocardium.

Animals↗
PubMed1986

Induction of neoplastic lesions in the livers of C57BL x C3HF1 mice by chloral hydrate.

Chloral hydrate is a compound of environmental significance. The current investigation was undertaken to evaluate the carcinogenic effect of chloral hydrate, because it is present in drinking water and it is also used as a sedative. Fifteen-day-old C57BL x C3HF1 male mice were given a single dose of chloral hydrate in distilled water at two dose levels: group 1, 5 micrograms/g BW; group 2, 10 mu/g BW (20-25 mice per group). Thirty-five mice given distilled water only served as controls. Animals were sacrificed at 24 hr and thereafter at various intervals up to 92 weeks. The entire liver was fixed and examined histologically. Mice sacrificed between 48 and 92 weeks showed hepatic lesions ranging from hyperplastic to trabecular carcinomas. The tumor incidence in mice given 10 micrograms/g chloral hydrate (six of eight) was significantly higher (P less than 0.05) than the incidence in the controls (two of 19). These findings indicate that chloral hydrate should be more thoroughly studied for potential carcinogenicity.

Animals↗
PubMed1985

Stereopathy of the renal papilla: a stereomicroscopic autopsy study.

Routine examination of the renal papilla with a stereomicroscope in 372 autopsies revealed a number of unexpected findings, including linear scarring of the papilla and marked vascular dilation of papillary vessels in black patients with sickle hemoglobinopathies, the presence of small tumors, and the rarity of papillary necrosis of the type seen in analgesic abuse. Stereomicroscopy also allows accurate documentation of the pattern and frequency of calcium deposition on the surface of the papilla (54.03 per cent of cases) and the incidence of early and well-formed calculi (8.06 per cent). Use of the stereomicroscope once again proved to be of inestimable value in routine autopsy service.

Adolescent↗
PubMed1983

Neurilemomas and salivary gland tumors of the head and neck following childhood irradiation.

In a program to contact and examine 4180 individuals with a history of childhood irradiation treatment for enlarged tonsils and adenoids, the authors have discovered 29 neurilemomas, two neurofibromas, and one ganglioneuroma in the 2311 subjects who have been found. Ten of these presented as acoustic neuromas, 21 presented as cervical mass lesions, and one was found in the superior posterior mediastinum. Because of their numbers and their strict localization to the area of treatment, it was concluded that they were radiation-induced. Analysis of the latency of these tumors indicates that they continue to occur for at least 30 years after the radiation exposure. In the same group of individuals, there have been 54 confirmed salivary gland tumors, 40 benign and 14 malignant. These tumors are also continuing to occur many years after the radiation exposure.

Adenoids↗
PubMed1983

Submitral atheromatous lesions in monkey and man.

Posterior submitral recess (PSMR) calcification is a common autopsy finding in elderly people, but its pathogenesis is undetermined. In this communication we show that, in part at least, the PSMR changes at autopsy are atheroma-like with lipid around the sclerosis and calcific deposits. These changes in the PSMR showed a statistically significant correlation with the presence of hypertension and with an autopsy finding of severe coronary atherosclerosis. We showed, for the first time, that similar fibrosis and lipid deposition in the PSMR can be produced in high-fat, high-cholesterol fed macaque monkeys (Macaca arctoides) with or without concomitant experimentally produced hypertension. It is concluded that changes in the PSMR in monkeys and man are strongly related to atherosclerosis and hypertension.

Adult↗
PubMed1983

Bone fragment emboli in the lungs of patients undergoing bone marrow transplantation.

In a study of biopsy and autopsy specimens from the lungs of patients undergoing bone marrow transplantation, we noted the presence of hematoxyphilic material within pulmonary vessels. This material, which consisted of calcium, was observed in arteries, arterioles, and capillaries. There were 12 specimens (two from open lung biopsies and 10 from autopsies) and all showed these emboli of calcified fragments. These bony spicules are derived from bone fragments in the grafted marrow and not from degenerative changes in the fatty marrow. The emboli are not associated with any significant pathologic change.

Bone Marrow Transplantation↗
PubMed1983

Pneumocystis pneumonia: importance of gallium scan for early diagnosis and description of a new immunoperoxidase technique to demonstrate Pneumocystis carinii.

Pneumocystis pneumonia presented in a homosexual with fever, a normal chest radiograph, and pulmonary gallium uptake. Bronchial washings yielded Mycobaterium tuberculosis, but despite antituberculosis therapy he remained febrile, and gallium uptake in the lung increased. Subsequently, silver stain of transbronchial lung biopsy obtained 2 months earlier at the time that tuberculosis was diagnosed showed many Pneumocystis cysts in alveolar spaces. In contrast to Pneumocystis cysts in infected lung tissue from other humans, our patient's Pneumocystis cysts reacted more avidly with antiserum to rat Pneumocystis than with antiserum to human pneumocystis, raising the possibility that organisms that infect humans may have varied surface antigenic properties.

Adult↗
PubMed1983

Diffuse phlegmonous gastroenterocolitis in a patient with an infected peritoneo-jugular venous shunt.

Phlegmonous gastritis and enterocolitis have been observed in association with alcoholism and hepatic cirrhosis. We report a case of diffuse phlegmonous gastroenterocolitis that occurred 1 yr after the insertion of a peritoneojugular venous shunt (Denver type) in a young male heroin abuser with postnecrotic cirrhosis. Diplococcus pneumoniae was cultured from the occluded distal tip of the shunt and the organism was visualized throughout the inflamed submucosa of the entire gastrointestinal tract. The diagnosis of this condition was not made premortem and the case highlights some of the clinical manifestations of this gastrointestinal disease. The possible pathogenetic mechanisms involved in this inflammatory process are discussed.

Adult↗